Chemistry 2

1. In the middle of the atom. 2. Contains protons and neutrons. 3. Has an overall positive charge. 4. Almost the whole mass is from the nucleus. 5. It is tiny to the rest of the atom.

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Give 6 things about the electrons.

1. Move around the nucleus. 2. Have a negative charge. 3. Tiny compared to nucleus. 4. Their determines how big the atom is. 5. Have little mass. 6. Occupy in shells around the nucleus.

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What does number of protons mean?

There is the same amount of neutrons.

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What charge does neutral atoms have?

No charge.

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What is the charge of the proton and the electron?

Proton positive and electron negative but both have the same number.

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What is different about the neutrons to the protons and electrons?

Neutrons always have a fixed number, they never change if there is a reaction or something.

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give the mass and charge of protons.

Mass: 1. Charge: +1.

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Give the mass and charge of neutrons.

Mass: 1. Charge: 0

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Give the mass and charge of the electrons.

Mass: 1/1800 Charge: -1

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Give 5 rules of the electron shells.

1. Occupy in shells. 2. Lowest are always filled first - closest to the nucleus. 3. Only the 1st shell has 2 electrons the rest has 8. 4. Like to be in full shells. 5. The outer shell is mostly not full, they want to react.

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Give 5 elements that consist of 1 type of atom.

1. Copper. 2. Aluminium. 3. Iron. 4. Oxygen. 5. Nitrogen.

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What is the atomic number?

How many protons there are in the atom.

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What does the mass number mean?

The total number of protons and neutrons in the nucleus.

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Define isotopes.

They are different atomic forms of the same element, which have the same number of protons but different numbers of neutrons.

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What is the rules with isotopes?

That they must have the same number of protons but a different mass number - normally neutrons change.

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What is the relative atomic mass and what is its sign?

This uses the average mass of the isotopes of one element. Ar(little r)

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What does relative atomic mass allow?

Relative atomic mass of each isotope and its relative abundance.

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What does relative abundance mean?

How much there is of each isotope compared to the total amount of the element in the world.

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How do you work out the relative atomic mass?

1. Multiply masses of each isotope by relative abundance. 2. Add them. 3. Divide by the sum of the relative abundance.

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What did scientists not know before Mendeleev discovered it?

In the 1800s they did know the structure of the atom but, they could measure the relative atomic mass. When they arranged the mass in order they found patterns in the properties.

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What did Mendeleev do?

He arranged the elements into groups by not sleeping for 3 days and 3 nights until he fell asleep and dream't about them all. They only knew about 50 element so they didn't have all the ones and, there were gaps.

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What did Mendeleev put the table in?

Placed elements with similar properties in vertical groups - gaps to make it work.

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What did this do for other scientists?

It helped them predict new elements and discovered the to fill in the gaps. A whole new group has been added - the nonreactive elements.

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Where are the metals and where are the non-metals?

Metals left side up to aluminium and a stairway down. Non-metals are the rest on the periodic table - right side.

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What are periods?

The rows in the periodic table that increase in the number of electrons. So, the period 1 has 1 electron and so forth.

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What are groups?

This is the columns. They go down the periodic table where they have similar properties has they have the same number of electrons on the outer shell. Group 1 has only 1 electron on its outer shell, and so forth.

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What does ionic bonding mean?

The transfer of electrons from positive or negative charged atoms called ions. This is because of the attraction of the opposite charge as they have a strong attachment.

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What does a shell with 1 electron do?

It gets rid of its electron because they only want full outer shells. If the get rid of the electron, then the element is called an ion.

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What does a shell with 7 electrons do>

It wants to gain one electron. They become ions. They are most likely to latch onto one in groups 1 or 2, depending on how many electrons they have.

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Groups 1 and 2 are...

...metals so they lose electrons to becomes + ions.

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What are + ions called?

Cations.

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Groups 6 and 7 are...

...non-metals so they gain electrons to becomes - ions.

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What are - ions called?

Anions.

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What are ionic compounds?

These are more than one element that transfer electrons to get a full outer shell.

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Give 5 properties of an ionic compound?

1. Have similar structure. 2. Closely packed regular lattice arrangement. 3. They are very strong electrostatic forces of attraction between the opposite charge. 4. They have high melting and boiling points. 5. They conduct electricity when molten/aq

Add dilute nitric acid to a silver nitrate solution. This will give a white precipitate of silver chloride.

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What is spectroscopy?

The patterns of light emitted can by the element in a flame is analysed. Each element produces a different pattern.

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Give 2 advantages of spectroscopy.

1. Fast. 2. Reliable.

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What has it helped scientists for?

Discovering new elements by the pattern produced by the light that hadn't been seen before.

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What is covalent bonding?

When two elements share electrons to fill their outer shells which forms a molecule.

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What are simple molecules?

These are substances that make very strong covalent bonds to form small molecules of 2 or more atoms.

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Give 5 things about simple molecules.

1. Inter-molecular forces are weak. 2. Melting and boiling points low. 3. Are usually liquid or gases at room temperature. 4. They don't conduct electricity. 5. You can tell what molecule it is by its physical state.

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What is a giant molecule?

They have a regular arranged lattice but with no charged ions.

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Give 5 things about giant molecules.

1. Strong bonds. 2. High melting and boiling points. 3. Graphite is the only one that does conduct electricity. 4. Are insoluble in water. 5. Examples: diamond and graphite.

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Describe dimonds. 3 things.

Has 4 covalent bonds with a rigid giant covalent structure, very hard, and doesn't conduct electricity due to no free electrons.

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Describe graphite. 3 things.

Forms 3 covalent bonds that create sheets of carbon atoms that slide over each other to make it lubricant. The layers hold together loosely - paper and pencil works. 3 of the 4 carbons form outer electrons for bonds and the others are delocalised.

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What does immiscible mean?

Liquids don't mix together.

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What does miscible mean?

Liquids do mix together.

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Give 2 ways of separating liquids.

1. Separating funnel. 2. Fractional distillation.

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Describe how you use a separating funnel.

1. Immiscible liquids stand separated in layers. 2. The denser liquid stays at the bottom. 3. Put them in a separating funnel and there is a tap that you release that takes up all the denser liquid. 4. E.G. Water and oil.

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Describe how you use fractional distillation.

1. Air is filtered to remove dust. 2. Cool to -200 where water vapour is released. 3. CO2 freezes and removed. 4. The container is heated. 5. Lowest melting point will go first through top of container as a gas, and you have the other liquid.

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By use fractional distillation?

Different boiling points from the liquids.

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What is chromatography?

Paper chromatography identifies different substances in a mixture that uses different substances wash through filter paper at different rates.

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Describe the procedure of chromatography - step 1:

1. Put a stop of each mixture being tested on a baseline on filter paper.

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Step 2:

2. Roll up the paper and put in a beaker full of solvent, like: water. The baseline should be above the solvent.

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Step 3:

3. The solvent steeps up the paper taking the samples with it.

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Step 4:

4. The different chemicals in the sample form separate spots on the paper.

Each element gets more electrons with less reactivity due to the positive nucleus and the electrons on the outer shells having a weak attraction to gain 1 or 2 electrons to fill the outer shell. They get a charge of - 1 or 2.

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What does displacement mean?

A more reactive element is displaces a less reactive element.

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Give an example in an equation.

CL2 + 2KL = L2 + 2KCL.

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What is group 0?

Noble gases.

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What happens as you go down the periodic table?

These elements are unreactive - inert. They gain electrons as you go down the periodic table. They have full outer shells so they don't need to react, they have no charge.

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Describe argon, helium and neon uses.

Argon is used in filament lamps so the energy isn't used up as they don't react - eco-friendly. Helium is less dense than air and can be used in balloons. Neon is used in advertisement signs as they get the audiences attention due to its brightness.

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What happens to the boiling point and density as you go down the periodic table.

They both increase.

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How do you break bonds?

Energy is required from chemical reactions where old are broken and new ones are formed.

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What is endothermic reactions with bonds?

Energy must be supplied to break existing bonds.

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What is exothermic reactions with bonds?

Energy must be supplied to form new bonds.

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What is an exothermic reaction?

It is when overall the energy is released to the surroundings in the form of heat shown by the rise in temperature.

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Give examples of enxothermic reactions.

Burning fuels gives out heat because it is forming new bonds in the product and gives out more energy. Explosions release a lot of heat also.

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What is endothermic reactions?

It is when overall the reaction takes in energy from the surroundings in the form of heat shown by the fall in temperature.

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Give examples of endothermic.

Photosynthesis uses light energy from the sun to convert into CO2. Ammonium nitrate dissolves in water to take in heat from its surroundings.

The higher the temperature, the quicker they move around as they have more energy. There are more frequent collisions.

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Describe high concentration.

If there is a higher concentration, there will be more particles that can bump into each other as there is less space so they are more compact. The pressure of the being compact makes more frequent collisions.

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Describe large surface area.

The bigger the surface area, they more collisions due to more area to react with.

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Describe catalysts.

A catalyst can make more collisions by speeding up the reaction by lowering the energy.

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Faster collisions cause...

...only a rise in temperature.

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The relative atomic mass is the...

..top number on the element.

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How do you find out the relative formula mass?

By timing the number of the element by the relative atomic mass.

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How do you find out the percentage mass?

(Number of atoms in the element X atomic mass / total mass of compound) X 100

1. Balance equation. 2. Work of atomic mass or the ones you want. 3. Divide to get 1 and multiply

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What is percentage yield?

The comparison of the actual yield and the theoretical yield.

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How do you find the percentage yield?

Actual yield/theoretical yield X 100.

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Give 3 disadvantages.

1. Incomplete reactions: yield is lower than expected. 2. Practical loss: when transferring you always lose some small amounts. 3. Unwanted reactions: you are always going to get some reactions that react with the oxygen.

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Give 3 things the do with the waste.

1. It costs money to through away waste. 2. Waste is harmful and disposing is expensive. 3. They make a profit out of it by using it up for other products.